Variegated, striped, marblized or mottled soap bars have been known for many years. Initially, as laundry soaps, they contained coloring materials, such as bluing agents, which functioned as aids for the whitening of clothing and textiles washed with the soaps. In recent years, however, interest in such bars has been primarily due to the possibility of producing attractive designs therein, which would be preferred by consumers. Thus, a marble pattern on a soap gives it a rich appearance and stripes or other similar configurations make the soap distinctive.
The manufacture of attractive variegated detergent bars is more difficult than the production of white soaps or these of a single color. To make the variegated products, it is important to mix the coloring agents with the soap to the correct degree. Too much mixing results in a completely colored product and too little mixing can produce an unatractive detergent bar. Furthermore, the nature of the blending of the coloring agent with the base detergent is relevant to the final design. Finally, although it is important to maintain the differently colored parts of the soap separate and distinct in appearance, they must be satisfactorily fused together so that they do not prematurely come apart in use and do not crack, become rough or pebbly at interfaces or dissolve at different rates.
Prior art methods of making variegated soap bars include: blendings of differently colored liquid soaps; pressing into cake form of soap powders; adding dyes or pigments to the vacuum chamber of a plodder; and blending together differently colored soaps, in solid form, and compacting them to bar or cake form. Many of these methods have met with a measure of success but the method of the present invention is particularly useful because it is readily adaptable to available equipment, is easily controlled and results in the production of a delicately marbled detergent bar or tablet.